Delta Printer prints High in front of each axis ?

I have a home built delta printer that prints and is working so so.. but something I just cant figure out.. if printing a circle say, it will print high in front of each axis and low between them. Kinda like image that I thinking posted. What do I need to adjust or what do I need to fix to get this to print a flat circle ?
Thanks.. btw.. first post new to fourm..
Greg
Attachment 2083

You're printing concave. You must adjust your delta radius, meaning it is too large.

thank you.. I will be fiddling with tomorrow now that I have an answer..

Yes, that will help you. I had to change mine by .06 and now its working fine.